Status bar brightness control
Fix status bar brightness control when on secure lock screen

When the notifications panel is disabled no views are handling touch events
on the status bar, so we see nothing beyond each ACTION_DOWN. Intercept touch
events when needed specifically for brightness control.

Also recycle VelocityTracker when we're not using it, as per its documentation.

Change-Id: I84d4c788bcdb1e05244710aca933d97e3e60d1b5
Status bar brightness control improvements

- Prevent brightness changes after notifications panel has been opened.
- Don't adjust brightness for swipes <45° from vertical.
- Stop using a VelocityTracker since we weren't actually giving it any
  events to track.

Change-Id: Ie28c5c186b692e3f308bba4a1ee02faeb0982ac1
Add 'Clear all recents' button
Add status bar native battery percentage